Conventional manholes include a lower or bottom pan, a barrel having a constant diameter adjacent the pan, a concentric or eccentric cone extending upwardly from the barrel, one or more adjusting rings to adjust the overall height of the manhole, and a casting frame on top of the adjusting rings to support a lid at an elevation substantially level with the surrounding pavement. The casting frame is preferably sealed to the uppermost adjusting ring to preclude or minimize water flow into the manhole. The cone and adjusting rings are commonly known as the manhole chimney. Most manhole structures are unique in size and shape, with varying diameters and depths.
The upper portion of the manhole is normally the weakest portion of the structure, due to traffic loading, freeze and thaw, impact from snow plows, and deteriorated small pieces of construction materials used to make the final grade adjustment for the surrounding road. Sub-standard construction methods can also lead to damage or deterioration of the upper manhole structure. Thus, the manhole chimney is vulnerable to allowing surface water and subsidence of soil to enter the manhole, which eventually leads to a structural failure of the manhole.
One method of repairing manholes involves cured-in place liners or sleeves. Due to the dimensional differences in manholes, these prior art repair liners are custom tailored for each specific manhole structure, which necessitates personal measurements for each manhole. Often times, the person must enter the manhole to measure difficult shaped structures. Such customization inherently increases costs for the one-of-a-kind liners.
The prior art liners generally are constructed of materials such as fiberglass or needle-punched felt material and PVC. These materials offer little or no stretching, particularly circumferentially. Due to the lack of stretchability in these prior art liner sleeves, it is critical that the manhole measurements be precise, which is nearly impossible. When measurements are not precise, the liner sleeve may be too small or too large. When the sleeve is too small, an annular space is created between the liner and the manhole structure, which allows surface water or ground water to migrate and enter the manhole, which subsequently enters the water collection system. When the liner is too large, a fold is created in the liner, which produces a rough inner surface, which reduces capacity for a person entering the manhole for maintenance and provides an area upon which obstacles may snag or catch. For example, if a bladder is used to expand the liner outwardly into engagement with the manhole walls, the bladder often becomes caught on the folds, which complicates removal of the bladder.
Therefore, a primary objective of the present invention is the provision of an improved method for repairing a manhole using a stretchable liner sleeve.
Another objective of the present invention is the provision of a universal liner that can be used to repair and renew manholes having various sizes.
A further objective of the present invention is the provision of a one-size fabric liner which stretches circumferentially to various diameters up to 150% of the unstretched diameter for use in manholes of varying sizes and shapes.
Another objective of the present invention is the provision of a method of repairing a manhole chimney by inserting a resin-impregnated sleeve into the chimney and stretching the sleeve circumferentially into engagement with the chimney, and then allowing the resin to cure in place so as to bond the sleeve to the chimney.
Another objective of the present invention is the provision of a method for repairing a manhole chimney using a sleeve which is inserted into the chimney and pressed into contact with the chimney, with the insertion and pressing steps being sequential or simultaneous.
A further objective of the present invention is the method of repairing a manhole chimney using a resin-coated sleeve which eliminates space between the sleeve and the chimney and which precludes folds in the sleeve after the sleeve is attached to the chimney.
Still another objective of the present invention is the provision of a stretchable liner for repairing manhole chimneys which is economical to manufacture, easy to install, and durable in use.
These and other objections will become apparent from the following description of the invention.